parallax

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. An apparent change in the direction of an object, caused by a change in observational position that provides a new line of sight.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. The change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of an observer.

n. The apparent shift of an object against a background due to a change in observer position.

n. The angle of seeing of the astronomical unit.

from the GNU version of the Collaborative International Dictionary of English

n. The apparent displacement, or difference of position, of an object, as seen from two different stations, or points of view.

n. The apparent difference in position of a body (as the sun, or a star) as seen from some point on the earth's surface, and as seen from some other conventional point, as the earth's center or the sun.

n. The annual parallax. See annual parallax, below.

from The Century Dictionary and Cyclopedia

n. An apparent displacement of an object observed, due to real displacement of the observer, so that the direction of the former with reference to the latter is changed.

n. In optics, an apparent shifting of the spider-lines in a telescope-reticle as the eye is moved before the eyepiece: it is due to the non-coincidence of the threads with the focal plane of the object-glass.

Etymologies

(American Heritage® Dictionary of the English Language, Fourth Edition)

Examples

"Do not let us fear," wrote Lalande in his _Astronomie des Dames_, "do not let us fear to use the term parallax, despite its scientific aspect; it is convenient, and this term explains a very simple and very familiar effect."

The term parallax proving “caviare to the general,” they further explained that it meant the angle formed by the inclination of two straight lines drawn from either extremity of the earth’s radius to the moon.

To be able to do this, astronomers have developed what's known as parallax, which is then used to calibrate distance indicators for objects further away, which are then used to calibrate even further objects, etc ....

One method uses what is known as a parallax barrier in front of a conventional liquid-crystal display screen, a layer of material with precisely placed slits that allow each eye to see a different set of pixels on the display.